The extension comes at an estimated cost of about $12 million a year to the city in foregone taxes, according to a spokesman for the state Department of Budget (the state budget is not affected).

The extension, pushed by Assembly Speaker Sheldon Silver and State Senator Daniel Squadron, is the latest in a series of added or extended subsidies for Lower Manhattan, a reminder that many of the benefits once billed as temporary are here to stay for a while.

The rationale, pushed by the elected officials and the Downtown Alliance: It’s a recession and redevelopment of the World Trade Center and other infrastructure has been slower than imagined, making the subsidies crucial for Lower Manhattan to attract business. “These incentives mean jobs and continued economic development throughout Lower Manhattan and will spur more businesses to relocate, renovate, and expand throughout the area,” Mr. Silver said in a statement.

The commercial rent tax abatement—the deadline for which tenants must have signed leases—was due to expire Wednesday, but, under the legislation, the end date would be pushed to 2014.